In this paper, we report the preliminary development of a fiber coupled microfluidic flow cytometer with its potential
application of sorting the very small embryonic like (VSEL) stem cells out of a mixture of platelets and VSEL stem
cells. The identification of a VSEL stem cell from a platelet is based on the large difference of their abilities to scatter
light. A simple cytometer prototype was built by cutting the fluidic and other channels into a polymer sheet and bonding
it with epoxy between two standard glass slides. Standard photolithography was used to expose an observation window
over the upper coated glass to reduce background scattered light. Liquid sample containing micro-particles (such as
cells) is injected into the microfluidic channel. Light from a 532-nm CW diode laser is coupled into the optical fiber that
delivers the light to the detection region in the channel to interrogate the flowing-by micro-particles. The scattering light
from the interrogated micro-particle is collected by a photodiode placed over the observation window. The device sorts
the micro-particle into the sort or waste outlet depending on the level of the photodiode signal. We used fluorescent latex
beads to test the detection and sorting functionalities of the device. It was found that the system could only detect about
half of the beads but could sort almost all the beads it detected.
The characterization of single biological cells in a microfluidic flow by using a 2D light scattering microfluidic
cytometric technique is described. Laser light is coupled into a microfluidic cytometer via an optical fiber to illuminate a
single scatterer in a fluidic flow. The 2D light scattering patterns are obtained by using a charge-coupled device (CCD)
detector. The system is tested by using standard polystyrene beads of 4 μm and 9.6 μm in diameter, and the bead
experimental results agree well with 1D Mie theory simulation results. Experiments on yeast cells are performed using
the microfluidic cytometer. Cell results are studied by finite-difference time-domain (FDTD) method, which can
simulate light scattering from non-homogeneous cells. For example, a complex biological cell model with inner
mitochondrial distribution is studied by FDTD in this paper. Considering the yeast cell size variations, the yeast cell 2D
scatter patterns agree well with the FDTD 2D simulation patterns. The system is capable of obtaining 2D side scatter
patterns from a single biological cell which may contain rich information on the biological cell inner structures. The
integration of light scattering, microfluidics and fiber optics described here may ultimately allow the development of a
lab-on-chip cytometer for label-free detection of diseases at a single cell level.
An integrated microfluidic planar optical waveguide system for measuring light scattered from a single scatterer is described. This system is used to obtain 2D side-scatter patterns from single polystyrene microbeads in a fluidic flow. Vertical fringes in the 2D scatter patterns are used to infer the location of the 90-deg scatter (polar angle). The 2D scatter patterns are shown to be symmetrical about the azimuth angle at 90 deg. Wide-angle comparisons between the experimental scatter patterns and Mie theory simulations are shown to be in good agreement. A method based on the Fourier transform analysis of the experimental and Mie simulation scatter patterns is developed for size differentiation.
We developed a novel finite-difference vector beam propagation method for three-dimensional waveguide structures. The method uses a vector electric field propagating in an inhomogeneous medium under slowly varying envelope approximation. The form birefringence and the coupling between transverse field components are taken into account. The scheme proposed for solving coupled paraxial vector wave equations is based on the operator splitting technique. The resulting algebraic equations are tridiagonal. The method is stable and very efficient.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.